The present invention relates to a shock isolation system for containers, and more particularly a shock isolation system for protecting sensitive cargo of containers during transfer of the containers to the deck of a ship at sea.
Containers housing sensitive equipment or cargo, such as jet engines, have traditionally required shock and vibration isolators to protect the cargo contained therein, particularly during helicopter transfer of the containers to a deck of a ship at sea. Typically, such isolators are in the form of elastomeric and/or wire rope coils provided within the container to support the load (i.e., cargo) and allow deflection of the load within the container when the container is subjected to a shock. More particularly, as the container comes into contact with a ship deck and ceases to travel further downward, the velocity and weight of the load contained therein continues to travel due to momentum against the opposing force of the isolators. The energy of the motion of deflection of the load is absorbed by the isolators and converted to heat. Such conversion results in the damping of vibrations and oscillations caused by the shock to the container. As such, the conventional isolators reduce the initial shock impact on the load and provide a certain amount of impact protection.
For all isolators, shock impact protection is provided by deceleration of the load and requires significant deflection of the load, particularly travel beyond the static position of the load. The allowable deflection of the load is therefore directly proportionate to the reduction of the impact upon the load. As such, for maximum shock protection, conventional isolation systems require a large spatial arrangement. That is, the containers must be of a very large size, such that the isolators within the container allow for maximum travel of the load; i.e., travel of the load within the container beyond the static position of the load. For example, with conventional isolators, if 24 inches of deflection in one direction is needed, the container would have to be at least 24 inches larger in the direction of the deflection.
Another well-accepted standard in the shipping industry is that the size of containers, and shipboard containers in particular, be as minimal as possible to facilitate easy handling and transport of the containers and to maximize the number of items that can fit on a particular ship. The minimum size requirement, however, is in conflict with the large container size required by conventional shock isolation systems.
Accordingly, there is a need for a shock isolation system which resolves this conflict. That is, there is a need for a shock isolation system which allows for a minimal container size, but also provides sufficient isolation of the container load against shock impacts.